This invention is directed to certain peroxide-curable tetrafluoroethylene-containing brominated fluoroelastomer compositions that contain N,N,N',N'-tetrasubstituted 1,8-diaminonaphthalenes that function as mold release agents and do not detrimentally affect the physical properties of the polymer.
When cured with peroxides tetrafluoroethylene-containing fluoroelastomers that contain units derived from brominated olefins have good resistance to damage by heat, solvents and corrosive chemicals and they are characterized by being especially resistant to degradation by steam and strong bases. However, the manufacture of molded products made from these polymers presents a serious problem because, in spite of the fact that mold release agents are sprayed on the mold cavity or incorporated in the polymer, the vulcanizates tenaciously adhere to the walls of the mold cavity and, consequently, the shaped article is frequently torn or damaged when removed from the mold. Also, the incorporation of a mold release agent into the polymer can, and usually does, have serious adverse effects on the physical properties of the vulcanizate, for example, Mooney Scorch and compression set, which can restrict the successful commercial use of the polymer. Deposits of polymer on the mold cavity surface and poor release of the shaped vulcanizate from the mold are major reasons for rejecting the shaped article which, of course, adds to the expense of manufacture of such molded articles. The present invention provides a peroxide-curable tetrafluoroethylene-containing fluoroelastomer composition containing aromatic diamines which are N,N,N',N'-tetrasubstituted 1,8-diaminonaphthalenes. These compositions do not stick to the metal mold cavity and tear when ejected or removed from the mold cavity while, at the same time, the incorporation of the aromatic diamine into the polymer does not detrimentally affect its important physical properties such as compression set resistance, elongation at break and tensile strength.